NASA scientists have combined starlight from two
of the largest telescopes on Earth to form an extraordinary new
tool in the search for planets outside the solar system.

March 15, 2001 -- Proving that two telescopes are better
than one, NASA astronomers have combined starlight from a pair
of Hawaiian 10-meter (33-foot) telescopes, creating an "optical
interferometer" with the resolving power of a huge single
telescope 85 meters wide -- nearly the size of a football field.

This
successful test at the W.M. Keck Observatory on Mauna Kea makes
the linked telescopes, which together are called the Keck Interferometer,
the world's most powerful optical observing system. The project
will eventually search for planets around nearby stars and help
NASA design future space-based missions that can search for habitable,
Earth-like worlds.

Right: At the summit of Mauna Kea, Hawaii, NASA astronomers
have linked the two 10-meter (33-foot) telescopes at the W.M.
Keck Observatory. [more]

"Successfully combining the light from two of the largest
telescopes on Earth is a fabulous technical advance," said
Anne Kinney, director of NASA's Astronomical Search for Origins
program, which includes the Keck Interferometer project.

Paul Swanson, the Keck Interferometer project manager at NASA's
Jet Propulsion Laboratory (JPL) agreed. "This is a major
step in the creation of a whole new class of astronomical telescopes.
Historically, breakthrough technologies like the Hale 200-inch
and the Hubble Space telescopes have made discoveries way beyond
the purpose for which they were originally built."

Since 1995, astronomers have discovered almost 50 planets
orbiting other stars. With current technology, which relies mainly
on radial velocity (or "Doppler
Shift") techniques to detect planets in an indirect
fashion, they can find very large worlds, 300 times as massive
as Earth, that are located close to their parent stars. Such
planets -- called "Hot
Jupiters" -- are not likely to harbor life as we know
it.

Using
a technique called interferometric
nulling, scientists hope to directly detect Hot Jupiters
with the Keck Interferometer. The powerful pair of telescopes
might also reveal planets farther from their parent stars, which
means their reflected light would be dimmer and harder to detect.

Left: Nulling is a process that reduces the light recorded
from the central star of a planetary system, while leaving the
planet's light undimmed. Credit: Terrestrial Planet Finder.

Nulling might also reveal faint dusty disks surrounding nearby
stars, a telltale sign of planetary systems. Our own solar system
is permeated with space dust. (The elusive Zodiacal Light, which
sharp-eyed sky watchers can spot in the night sky, are sunlight
reflected from interplanetary dust.) These tiny particles are
leftovers from the formation of the planets billions of years
ago, along with bits of debris from comets and asteroids. The
amount of such dust orbiting other stars is poorly known, but
perhaps not for long. The Keck Interferometer can sense clouds
of so-called "exozodiacal
dust" comparable in size to the dust swarm inside our
own solar system.

Exozodiacal dust is a noise source for future space missions
like the Terrestrial Planet
Finder (TPF), an interferometer that will seek out Earth-like
planets by looking directly for their infrared emissions. By
probing exozodiacal dust around nearby stars and by testing key
technologies, the Keck Interferometer will be an important pathfinder
for the TPF.

On Monday, March 12, 2001, starlight from HD61294, a faint
star in the constellation Lynx, was captured by both Keck telescopes
and transported across a sophisticated optical system spanning
the 85 meters (275 feet) separating the two telescopes. In an
underground tunnel the collected light waves were combined and
processed with a beam combiner and camera. In order to properly
phase the two telescopes, adaptive optics removed the distortion
caused by the Earth's atmosphere.

"This first light from the Keck Interferometer marks
a dramatic step forward and will help us accomplish the ultimate
goal of the Origins Program -- to search for signs of life beyond
by examining the light from 'Earths' orbiting nearby stars,"
said Charles Beichman, the Origins chief scientist at JPL.

Testing will continue for the next several months. Limited
science operations, including the search for planets, are expected
to begin this fall. Scientists around the world will soon be
invited to propose studies they would like to conduct using the
Keck Interferometer. Their proposals will undergo a formal review
and selection process.

The development of the Keck Interferometer is managed by
JPL for NASA's Office of Space Science, Washington, D.C. JPL
is a division of the California Institute of Technology in Pasadena.
The W.M. Keck Observatory is funded by Caltech, the University
of California and NASA, and is managed by the California Association
for Research in Astronomy, Kamuela, Hawaii.

NASA
Origins Program -- NASA's
Origins Program seeks to answer two enduring human questions
that we once considered around ancient campfires, yet still keep
alive in today's classrooms: Where do we come from? Are we alone?

The Science and Technology Directorate at NASA's
Marshall Space Flight Center
sponsors the Science@NASA web sites. The mission of Science@NASA is to
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